D for the same reason percents
The 11th triangular number = 66
To solve the inequality 

The numerator
is not factorizable.
so factor the denominator
:

Now take 
Then we get factor of the denominator as 
Thus 
Now 
Signs of 

is the required solution of the given inequality.
Answer:
1) At least 6.
2) $2194.8
3) $2326.49
4) 38 mph on average.
Step-by-step explanation:
Comment if you do need the steps
C; On this line, any two values have to add to 2.